BMC Med . Impact of baseline SARS-CoV-2 antibody status on syndromic surveillance and the risk of subsequent COVID-19-a prospective multicenter cohort study

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BMC Med


. 2021 Oct 14;19(1):270.
doi: 10.1186/s12916-021-02144-9.
Impact of baseline SARS-CoV-2 antibody status on syndromic surveillance and the risk of subsequent COVID-19-a prospective multicenter cohort study


Philipp Kohler ¹ , Sabine Güsewell ² , Marco Seneghini ³ , Thomas Egger ³ , Onicio Leal ^{4 5} , Angela Brucher ⁶ , Eva Lemmenmeier ⁷ , J Carsten Möller ⁸ , Philip Rieder ⁹ , Markus Ruetti ¹⁰ , Reto Stocker ⁹ , Danielle Vuichard-Gysin ¹¹ , Benedikt Wiggli ¹² , Ulrike Besold ¹³ , Stefan P Kuster ¹⁴ , Allison McGeer ¹⁵ , Lorenz Risch ^{16 7 17} , Andrée Friedl ¹² , Matthias Schlegel ³ , Pietro Vernazza ³ , Christian R Kahlert ^{18 19}



Affiliations

• PMID: 34649585
• DOI: 10.1186/s12916-021-02144-9

Abstract

Background: In a prospective healthcare worker (HCW) cohort, we assessed the risk of SARS-CoV-2 infection according to baseline serostatus.
Methods: Baseline serologies were performed among HCW from 23 Swiss healthcare institutions between June and September 2020, before the second COVID-19 wave. Participants answered weekly electronic questionnaires covering information about nasopharyngeal swabs (PCR/rapid antigen tests) and symptoms compatible with coronavirus disease 2019 (COVID-19). Screening of symptomatic staff by nasopharyngeal swabs was routinely performed in participating facilities. We compared numbers of positive nasopharyngeal tests and occurrence of COVID-19 symptoms between HCW with and without anti-nucleocapsid antibodies.
Results: A total of 4812 HCW participated, wherein 144 (3%) were seropositive at baseline. We analyzed 107,807 questionnaires with a median follow-up of 7.9 months. Median number of answered questionnaires was similar (24 vs. 23 per person, P = 0.83) between those with and without positive baseline serology. Among 2712 HCW with ≥ 1 SARS-CoV-2 test during follow-up, 3/67 (4.5%) seropositive individuals reported a positive result (one of whom asymptomatic), compared to 547/2645 (20.7%) seronegative participants, 12 of whom asymptomatic (risk ratio [RR] 0.22; 95% confidence interval [CI] 0.07 to 0.66). Seropositive HCWs less frequently reported impaired olfaction/taste (6/144, 4.2% vs. 588/4674, 12.6%, RR 0.33, 95% CI 0.15-0.73), chills (19/144, 13.2% vs. 1040/4674, 22.3%, RR 0.59, 95% CI 0.39-0.90), and limb/muscle pain (28/144, 19.4% vs. 1335/4674, 28.6%, RR 0.68 95% CI 0.49-0.95). Impaired olfaction/taste and limb/muscle pain also discriminated best between positive and negative SARS-CoV-2 results.
Conclusions: Having SARS-CoV-2 anti-nucleocapsid antibodies provides almost 80% protection against SARS-CoV-2 re-infection for a period of at least 8 months.

Keywords: COVID-19; Healthcare workers; Re-infection; Surveillance.